Furnace



G. R. PRATT Nov. 26, 1929.

FURNACE Filed July 3. 1926 G.R.Pratt v .By l

Patented Nov. 26, 1929 UNITED STATES PATENT erica FURNACE Application filed July 3, 1926.

The invention relates to improvements in furnaces and particularly coal burning furnaces and wherein the furnace is utilized for heating a water circulating system and an object of the invention is to provide a simple, economical and efcient device whereby fuels Which are high in gaseous matter such as soft coal can be properly ignited and the heat so K produced transferred to the liquid to be heated without undue loss of heat up the chimney.

A further object is to provide a means for maintaining the walls of the fuel chamber at an average or mean temperature for the pure. K pose of permitting the fuel to burn freely without attaining a temperature high enough to create clinkering due to the fusion of the ash and further to provide a means of maintaining the combustion space over the fuel bed neither too cool for the proper ignition of the combustible gases nor too hot to create undue smoke and soot deposits. v

A further object of the invention is to provide a water heating furnace having the construction and design of the combustion chami ber and the flues such that the products of combustion flow for a considerable part of their travel counterwise or opposed to the flow of the liquid being heated and such that A a positive flow of the liquid is maintained in the required direction.

l/Vith the above more important objects in view, the invention consists essentially in the arrangement and construction of parts hereinafter more particularly described, reference being had to the accompanying drawing, in which Fig. 1 is a vertical sectional view through the furnace, the section being taken in the plane denoted by the line 1-1 Figure 3.

Fig. 2 is a horizontal sectional view through the furnace, the section being taken in the plane denoted by the line 2-2 Figure 1. Fig. 3 is a vertical cross sectional view r through the furnace, the section being taken in the plane denoted by the line 3-3 Figure 1. Fig. 4 is a perspectiveview of the various water pipes. y n

In the drawing like characters of refer- Serial No. 120,399.

ence indicate corresponding parts in the several figures.

It is a well known fact that if fuel is to be burned in a relatively small chamber, the walls of which are maintained cool, the fuel is prevented from burning freely thus wasting good fuel in the ashes and further if the walls are maintained very hot, the temperature of the fuel bed is increased above that at which the ash melts thereby causing clinkers which latter prevents the fuel from burning freely. e

Further where fuel having a large gaseous constituent such as soft coal is being burned, it is found that if the combustion space is too cold, the gases are cooled 0H below theirl ignition temperature and are wasted up the flue unburnt and that if the walls of the combustion chamber are very hot, the gases are dissipated from the coal so quickly that they cannot be retained in the combustion chamber long enough to become properly ignited thereby causing dense smoke, soot and tar deposits with the consequent wasting of heat value. The present invention now described is designed to overcome the aforesaid difliculties and whilst obtaining also other desirable advantages.

Within the lower part of the furnace casing 1, I mount the customary gratos 2 above which is the fuel space 3 and the combustion chamber 4l. This casing is preferably air tight and of fire resisting material. rlhe top of the combustion chamber is closed by a top plate 5 hav-ing a central opening 6 therein and a baille plate 7 underlying the opening and extending downwardly into the combustion chamber.

I line the inside of the casing with a refractory material 8 such as lire brick or iron and Within such refractory material, I imbed a plurality of suitably spaced vertically disposed water tubes 9, the upper ends of which are connected to a continuous toptube 10 and the lower ends of which are connected to a continuous lower tube 11. The tubes have their inner sides exposed to the combustion chamber. Superimposed on the top of the combustion chamber t is a heatingl chamber' 12, the walls of which are composed 0f fire resisting material and' this chamber is connected to the combustion chamber through the passage reserved at 6 above the baffle plate. The heating chamber 12 communicates with the upper part of a vertically disposed side chamber 13, the walls of which are also formed from a refractory material and the side chamber is supplied with a centrally located vertically extending divisional wallll, the lower end of which is spaced from the bottom of the side chamber thereby providing a substantially U-shaped passageway between the chamber 12 and the flue 15 leading from the. upper end of the chamber 13 and communicating with the customary chimney.

At or near the top of the chamber 12 l locate a plurality of suitably spaced horizon- Jtally disposed water tubes 16, all of which have oneL end connected to a header tube 1? and the other end bent in a substantially U-shaped manner as indicated at 16 and connected to a second header tube 18. lt will be observed that the U-shaped bends in the latter pipes are in the chamber 13 and that they span the divisional wall 141. A water inlet tube 19 communicates with the header tube 18. The header tube 17 is connected by a tube 20 t0 the pipe 11, it being here observed that the tube 2O passes to the exterior of the furnace casing. An outlet tube 21 leads from the upper tube. 10. Y

Where the furnace is being utilized to heat water for a water circulating system, the water flows to the furnace from the system through the tube 19 and to the system from the furnace through the tube 21. A -door indicated at 22 is provided to permit fuel to be placed in the' fuel chamber on the grates.

In the operation of the furnace, I place the fuel to becons'umed on the grates, igniteit and supply it with the necessary air in the usual manner through the grates. The heat formed by the combustion of the fuel is radiated to the walls of the chamber l and by the passage of the ignited gases over the chamber walls. The ignited gases are deflected by the baffle Z and become mixed with the air which has been admitted to the combustion chamber in the usual manner and then pass through the opening 6 into the heating chamber where they expand into Aand lill such chamber and surround the tubes 16 heating them to a high temperature. The fact that heated gases by their differences in weight tend to rise and remain at the highest point is taken advantage of by superimposing the chamber 12 over that numbered t.

. Further the divisional wall 141 materially aids in retaining the heated gases in the chamber 1 2 so that the heat may be better absorbed by the liquid passing through the tubes 16. As the gases become cool, they slowly flow from the chamber 12 to the outlet 15 going under the lower end of the divisional wall 14 in their passage.

Particular attention is called to the fact that the tubes 16 are in the area of the greatest intensity of heat in the chamber 12 and it is further to be noticed that they are formed in the shape of an inverted siphon around the baffle wall 14, this latter preventing any intercirculation between the tubes 16. Accordingly any heat developed in any one tube or all tubes must pass out through the discharge header 17 due to the reaction of the difference in the specific gravity of the liquid contained in the inverted siphon and that in the. tubes 16 a positive flow is accordingly created which can only take place in one direction.

llt is to be noticed also that the tube 20 is kept away from Contact with the heat of the lire so that there is no retarding of the down 'ward flow of the liquid through such tube.

The heat of the ire tends to cause an upward flow of the liquid through the tubes 9 to the top tube 1G and in this connection l might remark that the relative positions of vthe tubes 9 in respect to the tube 20 is similar to an inverted Siphon and as the heat is applied to one leg only of such siphon, there is a positive movement of the liquid upwardly within the tubes 9.

The flow f the liquids in the tubes is also designed to maintain the wall of the furnace at an average or mean temperature, not too hot or not too cold and such results in the better burning of the fuel and of the gases, the reason of which was hereinbefore fully explained.

What VI claim as my invention is 1. The combination with the main combustion chamber of a water heating furnace, of a heating chamber superimposed on the combustion chamber and communicating there with, said heating chamber being provided vwith a side extension having a divisional wall therein forming inner and outer yconnected legs, a header tube located in ther upper part of the outer leg,a water inlet tubecommunieating with the header tube, water tubes lo cated in the upper part of the'heating chamber and extending in a Ushaped manner underneath the divisional wall and connected at their ends to the header tube,"a header tube connecting the other endsof said. latter tubes, a plurality of heating tubes `coniained'in the combustion chamber and having their upper and lower ends interconnected, a water tube connecting the latter header tube to the lower ends of the latter tubes and an outlet tube communicating with the upper ends of the water tubes within the combustion chamber.

2. A water heating furnace comprising a combustion chamber, ay heating chamber superimposed thereabove and communicating with the combustion chamber, a bame plate interposed between the chambers, a vertically disposed extension chamber communicating with the heating chamber, said extension chamber having a vertically disposed divisional wall therein providing a substantially U-shaped iiue, a header tube in the outer end of the iiue, a water inlet tube communicating therewith, a header tube in the upper part of the heating chamber remote from the flue, a plurality of water heating tubes connecting the header tubes and having U-shaped bends therein conforming to the shape of the ue, a plurality of vertically disposed water heating tubes located in the combustion chainber and having their upper and their lower ends interconnected by upper and lower tubes, a tube connecting the header tube within the heating chamber with the latter lower tube, said tube passing to the exterior of the furnace and a water outlet tube communicating with the latter upper tube.

3. The combination with the combustion chamber of a furnace, of a heating chamber superimposed on the combustion chamber and communicating therewith, a iiue connection,

. a U-shaped passage interposed between the flue and the heating chamber, and water heating tubes passing across the upper part of the heating chamber and extending through the U-shaped passage.

4. The combination with the combustion chamber of a furnace, of a heating chamber superimposed thereupon and having an opening centrally connecting the chambers, a baille plate underlying the opening and withi: in the combustion chamber, a vertically disposed chamber ormed as an extension of the heating chamber and extending therebelow and provided with an interior divisional wall forming a substantially U-shaped flue leading from the heating chamber, a header located in the upper part of the heating chamber in a position remote from the Unshaped flue, a header located in the upper part of the outer leg of the U-shaped flue, pipes connecting the headers and extending across the heating chamber and through the iue and inlet and out-let pipes leading to and from the headers.

Signed at Winnipeg, this 9th day of J une,

GEORGE ROBERT PRATT. 

